1. Field of the Invention
The present invention generally relates to welding equipment and in particular to equipment for removing the internal flash from pipe ends which have been welded together.
2. General Background
In laying continuous pipeline on land or offshore, a common method of welding the pipe sections together is by flash butt welding. In this type of operation the pipe sections are clamped together end-to-end and heated electrically by electrical contact shoes. As the temperature of each pipe end increases and reaches forging temperature, the pipe ends are forced together to expel molten metal and undesirable oxides and forge the two pipe ends together. This results in a considerable amount of slag or flash at the joint on the inner and outer surfaces of the pipe since the movement of the pipe sections toward each other may be two inches or more. Removal of the flash is necessary to facilitate application of a protective coating to the outside of the pipe, and smooth flow of whatever material is to be delivered through the pipeline. Removal of the interior flash is also beneficial for ease of movement of equipment such as cleaning pigs which may be run through the pipeline prior to placing it in service. Applicant is aware of the following equipment for removal of internal flash.
U.S. Pat. No. 4,383,786 entitled "Apparatus for Removing Flash from Pipes" discloses a body having V-shaped two-arm levers mounted thereon. Around the periphery of the body there are mounted cutting tool holders with each pivoted to one arm of each of the levers. Rollers which contact the inside surface of the pipe are mounted on the front and rear of the cutting tool holders and cutting tools are rigidly attached to the holders.
U.S. Pat. No. 3,103,834 entitled "Apparatus for Removing Burrs from the Inside of Pipes and the Like" discloses an inner cylinder which acts as a support for a tool carrying outer cylinder. The tool is rotated around its axis during cutting of the burr.
U.S. Pat. No. 2,237,550 entitled "Inside Flash Cutter" discloses a flash cutter supporting frame designed to cut flash along the longitudinal axis of the tube.